deficits [1]. Small injuries can result in transient impairments, but the mechanisms of recovery are poorly understood [2]. At the cortical level, rearrangements of the sensory and motor representation maps often parallel recovery [3, 4].
Results and discussion
In the sensory system, studies have shown thatAdult female Lewis rats were anesthetized, and their left cortical and subcortical mechanisms contribute to motor cortex was exposed and stimulated by a tungsten map rearrangements [5, 6], but for the motor system microelectrode as described in the supplemental materials the situation is less clear. Here we show that large-section, with the aim to identify an area that yields consisscale structural changes in the spared rostral part tent and exclusive hind-limb (HL) responses. Consistent of the spinal cord occur simultaneously with shifts with previous studies [8, 9], this was found to be the case of a hind-limb motor cortex representation after for stimulations at 2 mm caudal to bregma and 1.5-2.5 mm traumatic spinal-cord injury. By intracortical lateral to the midline. Stimulation at these coordinates microstimulation, we defined a cortical area that usually activated hind-limb flexor muscles and, more consistently and exclusively yielded hind-limb rarely, extensor muscles. In two animals, muscles of the muscle responses in normal adult rats. Four weeks tail base were activated. We determined the stimulus after a bilateral transsection of the corticospinal threshold by increasing stimulus intensities and recording tract (CST) in the lower thoracic spinal cord, we again the lowest intensity at which a consistent movement was stimulated this cortical field and found forelimb, observed [7]. The average threshold was 49.6 A (Ϯ 18.1 whisker, and trunk responses, thus demonstrating standard deviation [SD], n ϭ 32), and animals with threshreorganization of the cortical motor olds above 100 A were not used for physiological evaluarepresentation. Anterograde tracing of corticospinal tion. After the stimulation, the animals received an addifibers originating from this former hind-limb area tional dose of anaesthetic (xylazine), and the scalp wasrevealed that sprouting greatly increased the sutured. Subsequently, the spinal cord was exposed at a normally small number of collaterals that lead into mid-thoracic level (T8), and the dorsal columns, including the cervical spinal cord rostral to the lesion. We the main component of the corticospinal tract (CST), were conclude that the corticospinal motor system has transsected bilaterally as described [10]. Care was taken greater potential to adapt structurally to lesions than not to compromise the dorsolaterally running rubrospinal was previously believed and hypothesize that this tract (Figure 1). In a control group, the spinal cord was spontaneous growth response is the basis for the exposed but not transsected (sham operation). The tissue observed motor representation rearrangements overlying the spinal cord was sutured, and the animals and contributes to functional recov...